Exception : ResultSet is closed

Hi folks
I have a problem while closing the ResultSet in JDBC.
iam using Postgre DB, here for normal execution it is working fine,
but while we are doing load test at the rate of 30 or 40 hits to the
application on a peak volume it is throwing the error like
"PSQLException:This ResultSet is closed."
can you please let me know what are all the possibilities....
here is my DB releasing code..